The present invention relates generally radio frequency (RF) amplifiers and, more particularly, to RF amplifiers that have a switched attenuator function. Modern digital communications systems employ highly complex and highly precise modulation waveforms in order to maximize utilization and revenue from precisely assigned radio frequency band allocations. The front-end wireless receiver circuits for these sophisticated communications systems often require a switched attenuator function (for example, in the range of 10 to 30 dB) to suppress very strong signals either due to short transmission range or to unwanted high powers at long range. This suppression must keep the signal linear so that it may be properly processed by the receiving system, yet, at the same time, must not adversely affect the low noise amplification of weak desired signals in any way.
Typically this circuit is implemented with discrete components due to the high power involved and due to tight requirements on matching impedance and linearity. These components require significant printed wiring board (PWB) area and thus are costly for production communications systems. Accordingly, it would be highly desirable to provide an amplifier with a switched attenuator function, but without the foregoing disadvantages. The present invention is directed to this end.